So I noticed a few people wondering how to make stairs that go into the 2nd floor and I made a small guide on how I approached it. The guide is specifically for making the hole in the floor. Fitting stairs is something that takes trial and error with the dimensions/placements because for whatever reason there is no snap-to-grid for stairs in the level editor. If you have any questions lemme know.

http://imgur.com/a/Kh7Zo